feat(db-proxy): test connection before deploying (webiny#707)

Author: adrians5j

components/serverless-db-proxy/serverless.js

@@ -1,13 +1,32 @@
 const { Component } = require("@serverless/core");
 const get = require("lodash.get");
+const { MongoClient } = require("mongodb");
 
 class DbProxyComponent extends Component {
     async default(inputs = {}) {
-        const { env, region, concurrencyLimit, timeout } = inputs;
+        const { env, region, concurrencyLimit, timeout, testConnectionBeforeDeploy } = inputs;
+
+        if (testConnectionBeforeDeploy === true) {
+            try {
+                const connection = await MongoClient.connect(env.MONGODB_SERVER, {
+                    useNewUrlParser: true,
+                    useUnifiedTopology: true,
+                    connectTimeoutMS: 5000,
+                    socketTimeoutMS: 5000,
+                    serverSelectionTimeoutMS: 5000
+                });
+
+                // Let's immediately close the connection so we don't end up with a zombie connection.
+                await connection.close();
+            } catch (e) {
+                throw new Error(
+                    `Could not connect to the MongoDB server, make sure the connection string is correct and that the database server allows outside connections. Check https://docs.webiny.com/docs/get-started/quick-start#3-setup-database-connection for more information.`
+                );
+            }
+        }
 
         const name =
-            get(this.state, "output.name") ||
-            this.context.instance.getResourceName(inputs.name);
+            get(this.state, "output.name") || this.context.instance.getResourceName(inputs.name);
 
         const proxyLambda = await this.load("@webiny/serverless-function");
         const proxyLambdaOutput = await proxyLambda({

examples/api/serverless.yml

@@ -43,6 +43,7 @@ gateway:
 dbProxy:
   component: "@webiny/serverless-db-proxy/dist"
   inputs:
+    testConnectionBeforeDeploy: true
     region: ${vars.region}
     concurrencyLimit: 15
     timeout: 30

examples/apps/serverless.yml

@@ -9,6 +9,7 @@ vars:
 dbProxy:
   component: "@webiny/serverless-db-proxy/dist"
   inputs:
+    testConnectionBeforeDeploy: true
     region: ${vars.region}
     concurrencyLimit: 15
     timeout: 30

packages/cli/create/template/api/serverless.yml

@@ -42,6 +42,7 @@ gateway:
 dbProxy:
   component: "@webiny/serverless-db-proxy"
   inputs:
+    testConnectionBeforeDeploy: true
     region: ${vars.region}
     concurrencyLimit: 15
     timeout: 30

packages/cli/create/template/apps/serverless.yml

@@ -9,6 +9,7 @@ vars:
 dbProxy:
   component: "@webiny/serverless-db-proxy"
   inputs:
+    testConnectionBeforeDeploy: true
     region: ${vars.region}
     concurrencyLimit: 15
     timeout: 30